Operation CHARM: Car repair manuals for everyone.
Home >> BMW >> 2005 >> 325Ci Convertible (E46) L6-2.5L (M54) >> Repair and Diagnosis >> Powertrain Management >> Tune-up and Engine Performance Checks >> Compression Check >> Testing and Inspection
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Compression Check: Testing and Inspection


Checking Compression Of All Cylinders

- Read out fault memory of DME control unit
- Check stored faults
- Rectify faults
- Clear fault memory

Disconnect fuel pump relay or fuel pump fuse.
Start engine and allow remaining fuel to escape.
This prevents fuel from being injected, the catalytic converter from being damaged and the test result from being distorted during the compression pressure check.

Caution: High voltage - mortal danger!

Disconnect all supply leads from ignition coils (interrupt power supply to ignition coils).





Remove all spark plugs Service and Repair
Screw special tool 11 0 226 by hand into spark plug thread and connect special tool 11 0 224.

Note: Check that seal is in perfect condition.





Depress accelerator and actuate starter until compression stops rising.
Compression pressure Specifications

Now clear the fault memory.


pro multis · About Operation CHARM